Japanese knotweed

[norse]

I think you are right there, roundup does the trick, but maybe you need to go back again in year two and possibly a bit in year 3, not too big a job, but if left it will take over

I sprayed it in late spring when I was spot treating some docks etc in our grass paddocks and I thought that I would give the knot weed a blast and was very pleased with the results

 

[Redfish]

Stem injecting does work but for bigger sites its not practical and is only comparable to conventional spraying which works really well. Good coverage is really important and we use a variety of long/telescopic lances.
Best results are achieved spraying glyphosate as per label recommendations between the onset of flowering and senescence.

I would avoid digging/cutting or using neat glyphosate, its really easy to put the plant into dormancy and drag out control programmes!! Just be aware that even after the plant isn't producing new growth rhizomes can remain viable for significant periods of time.

 

[Ritchie]

Stem injection is the way to go.
You cant dig it up and bury it, if you miss a bit it grows again.
Spraying will also kill it, do NOT make it overly strong.
The other way is to bend it near the base and make it bleed itself to death with repeated bending throughout the year.


Ritchie

 

[Davey]

We had some on a site we were due to build on so got professionals in as they provided an insurance backed guarantee.

Apparently the worst thing you can do is disturb the roots as that sends it into a growth spurt.

Treat in situ, check for regrowth every year and repeat until gone.

 

[JohnDeere8530]

Many thanks for replies. Seems to me (and what I've done on a different far smaller site in the past) that spraying everything several times with a normal dose of Round Up is the way to go

Is it a waste of time now it's coming up to winter though? Ie is it best left to the spring now?

 

[Grassman]

Stem injection is for situations where spraying is not possible. For example in amongst desirable plants.
Spraying is the way to go. Get on with it now if it's still warm enough.

 

[Ritchie]

Remember to spray the stems as well if there's still green in there. It needs an overall spray but Not to the point of runoff.


Ritchie

 

[Farfrae]

Here you go, glyposate and timing of application is the key.

https://www.swansea.ac.uk/press-off...tistsleadthewayintacklingjapaneseknotweed.php

https://link.springer.com/article/10.1007/s10530-018-1684-5

 

[SilliamWhale]

I agree with those who say just keep using roundup. I had a problem area and you just need to keep at it - say 4 times a year for a few years. No need to go super silly on roundup rates either.

Tordon was a good chemical.

 

[Exfarmer]

I had knotweed in a garden of a property I purchased 30 years ago. As I did not want to kill everything in the area, I used roundup spot treatment on the leaves. It took a couple of years of 2-3 passes. I later found some growing 2-3 years after but killed it I think in one pass.
I was lucky that at most I had 40- 50 stems from memory.
We have used spot treatment using special guns from Holland for weed control of potatoes in onions, there again it was very important , never to use too strong a concentration or control would be poor, as the glyphosate would not translocate properly

 

[JohnDeere8530]

So what rate. Say 50 50 with water and cover everything but not to the point of run off?

 

[Farmer_Joe]

there was loads on road side near us, council must have sprayed it, killed it in one pass not sure what they used but nothings grown back 2 years later?

perhaps something to kill plant then i know theres weed killers that sit in soil from my training mostly used by councils for amenity stuff??? prob same active chemical though?

 

[marco]

Forefront T will sort it

 

[JohnDeere8530]

Seems the school of thought from scientific studies by Universities is that good old glyphosate is the best chemical to use

 

[Exfarmer]

So what rate. Say 50 50 with water and cover everything but not to the point of run off?

If you are referring to glyphosate, never more than 10%

 

[Darranfarm]

If stem injecting a meat inject gun is quicker than syringe. Strong glypho, not neat it won't take it in

 

[RushesToo]

I have seen it killed with normal glyphosate application, nothing special in mix, just attention to detail. This has been in hedges not gardens.
It is just a weed.

Persistence and swift attention to regrowth. Put it in your diary to check if you are likely to forget, more at first and less as it goes.

It does die it isn't a triffid.

 

[Grassman]

There are plenty making a lot of money out of knotweed and the myth you need experts to kill it.

 

[JohnDeere8530]

Ok I will spray it today with a 10% solution of Roundup and a wetter added for good measure. Seems this is the start of successive treatments!